diff --git a/addons/mrp/models/mrp_workorder.py b/addons/mrp/models/mrp_workorder.py
index e9732368212..69187efaf94 100644
--- a/addons/mrp/models/mrp_workorder.py
+++ b/addons/mrp/models/mrp_workorder.py
@@ -728,7 +728,8 @@ class MrpWorkorder(models.Model):
             duration_expected_working = (self.duration_expected - self.workcenter_id.time_start - self.workcenter_id.time_stop) * self.workcenter_id.time_efficiency / (100.0 * cycle_number)
             if duration_expected_working < 0:
                 duration_expected_working = 0
-            return alternative_workcenter.time_start + alternative_workcenter.time_stop + cycle_number * duration_expected_working * 100.0 / alternative_workcenter.time_efficiency
+            alternative_wc_cycle_nb = float_round(qty_production / alternative_workcenter.capacity, precision_digits=0, rounding_method='UP')
+            return alternative_workcenter.time_start + alternative_workcenter.time_stop + alternative_wc_cycle_nb * duration_expected_working * 100.0 / alternative_workcenter.time_efficiency
         time_cycle = self.operation_id.time_cycle
         return self.workcenter_id.time_start + self.workcenter_id.time_stop + cycle_number * time_cycle * 100.0 / self.workcenter_id.time_efficiency
 
diff --git a/addons/mrp/tests/test_order.py b/addons/mrp/tests/test_order.py
index c58488c8fb5..304e461aa88 100644
--- a/addons/mrp/tests/test_order.py
+++ b/addons/mrp/tests/test_order.py
@@ -2651,3 +2651,80 @@ class TestMrpOrder(TestMrpCommon):
         self.assertEqual(mo_3.state, 'to_close')
         mo_3.button_mark_done()
         self.assertEqual(mo_3.state, 'done')
+
+    def test_planning_workorder(self):
+        """
+            Check that the fastest work center is used when planning the workorder.
+            - create two work centers with similar production capacity
+                but the work_center_2 with a longer start and stop time.
+            1:/ produce 2 units > work_center_1 faster because
+                it does not need much time to start and to finish the production.
+            2/ - update the production capacity of the work_center_2 to 4
+                - produce 4 units > work_center_2 faster because
+                it must do a single cycle while the work_center_1 have to do two cycles.
+        """
+        workcenter_1 = self.env['mrp.workcenter'].create({
+            'name': 'wc1',
+            'capacity': 2,
+            'time_start': 1,
+            'time_stop': 1,
+            'time_efficiency': 100,
+        })
+
+        workcenter_2 = self.env['mrp.workcenter'].create({
+            'name': 'wc2',
+            'capacity': 2,
+            'time_start': 10,
+            'time_stop': 5,
+            'time_efficiency': 100,
+            'alternative_workcenter_ids': [workcenter_1.id]
+        })
+
+        product_to_build = self.env['product.product'].create({
+            'name': 'final product',
+            'type': 'product',
+        })
+
+        product_to_use = self.env['product.product'].create({
+            'name': 'component',
+            'type': 'product',
+        })
+
+        bom = self.env['mrp.bom'].create({
+            'product_id': product_to_build.id,
+            'product_tmpl_id': product_to_build.product_tmpl_id.id,
+            'product_uom_id': self.uom_unit.id,
+            'product_qty': 1.0,
+            'type': 'normal',
+            'consumption': 'flexible',
+            'operation_ids': [
+                (0, 0, {'name': 'Test', 'workcenter_id': workcenter_2.id, 'time_cycle': 60, 'sequence': 1}),
+            ],
+            'bom_line_ids': [
+                (0, 0, {'product_id': product_to_use.id, 'product_qty': 1}),
+            ]})
+
+        #MO_1
+        mo_form = Form(self.env['mrp.production'])
+        mo_form.product_id = product_to_build
+        mo_form.bom_id = bom
+        mo_form.product_qty = 2
+        mo = mo_form.save()
+        mo.action_confirm()
+        mo.button_plan()
+        self.assertEqual(mo.workorder_ids[0].workcenter_id.id, workcenter_1.id, 'workcenter_1 is faster than workcenter_2 to manufacture 2 units')
+        # Unplan the mo to prevent the first workcenter from being busy
+        mo.button_unplan()
+
+        # Update the production capcity
+        workcenter_2.capacity = 4
+
+        #MO_2
+        mo_form = Form(self.env['mrp.production'])
+        mo_form.product_id = product_to_build
+        mo_form.bom_id = bom
+        mo_form.product_qty = 4
+        mo_2 = mo_form.save()
+        mo_2.action_confirm()
+        mo_2.button_plan()
+        self.assertEqual(mo_2.workorder_ids[0].workcenter_id.id, workcenter_2.id, 'workcenter_2 is faster than workcenter_1 to manufacture 4 units')